Industrial truck with auxiliary lift



Feb. 6, 1962 J. A. DRAXLER 3,019,919

INDUSTRIAL TRUCK WITH AUXILIARY LIFT Filed March 31, 1958 2 Sheets-Sheet 1 FIG. I

V 30 FIG. 3 INYENTOR.

JOHN A. DRAXLER ATTORNEYS Feb. 6, 1962 J. A. DRAXLER 3,019,919

INDUSTRIAL TRUCK WITH AUXILIARY LIFT Filed March 31, 1958 2 Sheets-Sheet 2 INVENTOR. 6 JOHN A. DRAXLER BY 447M Jfi ATTORNEYS 3,019,919 INDUSTRIAL TRUCK WITH AUXILIARY LIFT John A. Draxler, lierea, Qhio, assignor to The Elwell- Parker Electric Company, Cleveland, Ohio, a corporation of Ohio Filed Mar. 31, 1958, Ser. No. 725,091 2 Claims. (Cl. 214.-82)

The present invention is concerned generally with an industrial lift truck for handling heavy loads, more particularly with a truck for handling heavy dies and specifically with an end-loading die handling truck provided with an auxiliary lift device.

Industrial lift trucks for transporting heavy dies between press and storage locations and for maneuvering the same in and out of a press bed are now well known in the prior art. However, in the case of trucks intended for comparatively heavy dies, for example on the order of 20,000 or 30,000 pounds, difficulties are at times encountered in maneuvering the die between the load supporting platform of the truck and a press bed or storage rack. This is particularly true with respect to presses with press bed levels below the minimum attainable load supporting truck platform height, where a difference in platform and bed levels impedes convenient safe transfer of the heavy load.

However, as the great Weight of the dies in question imposes certain restrictions on practical design of such trucks, the solution to such problems is not to be achieved by providing a truck with a low lift platform. Thus in truck design acceptable from viewpoint of cost, capacity and other vehicle characteristics, as a practical matter at least a certain size of vehicle wheels and tires must be used under the region of the die supporting platform; and this fact therefore limits the lowest level attainable by the lift platform surface. As a typical example for a lift truck with capacity for the above stated loads, a lowermost level of about 18 inches can be obtained in the platform surface, whereas many press installations may have a die supporting bed 12 inches above the service floor. Accordingly and obviously some difficulty is to be expected in drawing a heavy die from the bed onto the truck platform, or in the reverse operation; and special provision must be made to overcome the difference in level, if the load transfer is to be effected with safety to equipment and operators, where indeed it can be effected at all.

By the present invention there is provided an auxiliary lift device at the forward end of the lift platform in an end-loading truck, which bridges and overcomes the difference in level between the lowermost truck platform and the lower surface of the press bed or other situs. In essence this comprises a supporting roller device mounted at the front of the truck in such manner as permits raising the same by suitable motor means from a position well below the horizontal main load supporting surface of the platform, that is, also below the level of the external locus surface with respect to which the load is to be transferred, to a position preferably above the platform surface, whereby the die to be loaded or unloaded may be at least partially supported on a locally' engaging rolling member and tilted as required in movement between the two levels involved. In a lift truck, the combination of a lift platform having such auxiliary device with force applying means for pushing or pulling the load across the platform edge allows manipulation of the die between the diverse levels in question; and that conveniently, and in a manner safe with respect to operators, the die itself and environmental structures.

The general object of the present invention is then the provision, in an industrial lift truck for quite heavy 3,019,919 Pa nted. etal .363.

particularly rigid loads, of means for overcoming the difference in level between the load platform of the truck when at its lower-most position and a lower external level. Another object of the invention is the provision of an auxiliary lift means on the platform of a lift truck, whereby a die, being loaded or unloaded, may be sup; ported or raised or lowered for tilting of the same when the lowermost attainable platform level is above that of the actual or intended external situs for the lead. A still further object of the invention is the provision on an industrial truck of an auxiliary lift mechanism of the character described in combination with means furnish: ing a die translating force to move the die to or from the load carrying platform. Other objects and advan: tages will appear from the following description of one embodiment of the invention and the drawings wherein:

FIG. 1 shows in side elevation a lift truck embodying the present invention with certain parts broken away;

FIG. 2 is a fragmentary plan view of the front end of the truck shown in FIG. 1, showing in greater detail the structure of the auxiliary lift device and the adjacent platform structure;

FIG. 3 is a simplified schematic hydraulic circuit for operation of the auxiliary lift;

FIGS. 4-6, in schematic outline, show a typical sequence of manipulations for loading a die from a press bed to the lift platform of the truck disclosed in FIG. 1; and

FIGS. 7-9 show a typical sequence of manipulation in unloading a die from the truck platform to a press bed.

The invention is disclosed in the drawings as incorporated in an industrial lift truck of well known vehicle and lift platform structure, wherein there are designated by general reference numerals, a truck platform structure 10 rigidly secured for movement therewith to an elevator carriage 11 supported and guided for vertical movement by a vertical elevator frame structure 12. The platform includes an extended top load supporting surface 14 and at opposite sides a pair of movable stanchions 15, preferably independently movable along the length of the truck in tracks or slotted guideways 16;, the actuating mechanism for which in each case is enclosed beneath the level of platform surface 14 and within the corresponding side skirt 17 of the platform structure. To each stanchion a corresponding. load pusher arm 15a is pivotally removably secured at one end by a removable pivot pin permitting the arms to be swung up out of the way as indicated in solid lines in FIG. 1 or dropped down to reach out beyond the front of the platform when the stanchions are advanced, as indicated by dashed outlines. At the front end of the platform the horizontal load supporting surface 14 is terminated short of the verticalfront skirt 18 to which it is joined by an incline constituting a single plane or pair of slightly mutually inclined planes at 1411.

Generally speaking the vehicle structure per se, the elevator frame, carriage and platform, and the actuating means for stanchions 15 may be of any design suitable for the support and movement of the heavy loads here contemplated. Thus the elevator mechanism may be mechanically or hydraulically operated, and so also the stanchion powering system. Preferably, however, the stanchion actuating system may be that fully disclosed in US. Patent 2,756,885, issued July 1, 1956, particularly where a hydraulic elevator system is used.

The auxiliary lift mechanism, designated by the general reference character L and centrally located at the forward end of the platform having an opening to accommodate the same, includes a rigid assembly of arms 21 rigidly joined and spaced at their back ends by an interposed sleeve member 22 pivotally supported on a t-ransverse pivot shaft 23 mounted in suitable brackets beneath the platform surface member 14, whereby the assembly may be swung upwardly from the positions of FIGS. 1 and 2 for purposes to be described. As may be seen in FIG. 2, the rear parallel narrowly spaced arm portions 21a, somewhat greater than half the assembly in length, are respectively joined by sharply outwardly divergent portions to short parallel front portions 21b, widely spaced to accommodate a long central roller 25 rotatably supported therebetween on a transversely extending shaft 26 fixed in the arms. outwardly of each arm, the corresponding projecting ends of shaft 26 rotatably support shorter rollers 27 equal in diameter to 25. The straight portions 21b of the arms project beyond the plane of the front skirt 1% when the assembly is in lowermost position.

A single acting hydraulic cylinder unit 39 is pivotally supported by integrally attached trunnions on the lower end of the cylinder unit, suitable brackets, attached to the supporting frame of the platform structure, and the movable piston thereof has a piston rod 31 with an end yoke 31a pivotally connected between the arm portions 21a, at a point about a third of the assembly length from shaft 23, by a short pivot shaft 33 extending between the arms to form a third class lever. Thus the aligned rollers 25, 27 may be swung simultaneously from a lowermost position corresponding to contracted condition of the cylinder unit 30 by extension of the unit under hydraulic pressure to a position where the upper surface thereof is at least at the same level as the horizontal surface 14/ Accordingly the forward edges of the platform member 14 "and the inclined portion 14b and the upper region of the skirt 18 are cut out to accommodate the arm structure and permit its swinging motion over the range described.

Attached to the front skirt 18 is a forwardly projecting rectangular box structure 35 formed of front, side and preferably bottom plates welded into an upwardly open hollow integral structure generally surrounding the rollers 25, 27 in their lower-most position to serve as a bumper or guard therefor and also to provide a contact surface for manipulation of dies as hereinafter described. The cylinder unit 3! and arm assembly are located beneath the platform in a region which will clear the vehicle frame and the spaced paired sets of front wheels W beneath the platform; and the auxiliary lift assembly as a whole is centrally and symmetrically located at the front of the truck.

The cylinder unit 30 is here disclosed as a single acting system for extension under hydraulic pressure and contraction by the weight and mass of the rollers and arm assembly elevated thereby. Accordingly in FIG. 3 there is shown a simplified diagram of a hydraulic fluid supply and control system for actuation of the lift assembly, wherein P represents a pump driven by an electric motor or other means, drawing fluid from a reservoir R and delivering the same through a pressure relief valve C with a vent return or by-pass line to R, and control valve V to the lower end of cylinder unit 30.

The valve V is adapted preferably to a B-position or a 3-setting control, whereby when it is set to a first position fluid is directed from the pump P to the cylinder 30 to extend the same; when set to a reverse position, the cylinder 30 is connected to the reservoir R to permit exhaust of hydraulic fluid therefrom, and contraction of the cylinder unit under the Weight of the arm assembly; and at an intermediate position, it blocks flow of fluid to or from the cylinder unit 34} and thereby maintains the rollers at a selected position. The valve C is interposed between the pump exhaust and the valve V to limit pressure delivered by the pump P to the cylinder and to serve as a by-pass to the reservoir R when the pump P is operating and valve V blocks fluid flow to the cylinder.

Various types of control and power means for pump P can, of course, be used as are well known to the prior art and indeed the pump P, reservoir R can be part of a hydraulic system supplying other hydraulically actuated components of the truck mechanism. Likewise as it well known to the prior art the several components of the auxiliary lift hydraulic system, other than unit 30, may be located either on the lift platform or carriage or on the vehicle proper as other design considerations may dictate with suitable flexible hydraulic lines as may be required. The valve V, as a manual control valve, would of course be located at the particular control station provided for purposes of die or load manipulation.

In a truck structure as here disclosed the platform may be moved vertically to any selected position in the range indicated by the lowermost position shown in solid lines in FIG. 1 and the uppermost position of the dashed outline, as usual in lift trucks. The stanchions 15 with arms 1.5a removed may serve for attachment of cables, chains or the like which engage a die to draw the same toward the truck platform as in FIGS. 4-6. Alternatively, the stanchions may provide pusher means engaging a die on the platform to displace it forwardly along the platform. Preferably in the latter case, the stanchions are joined as in FIGS. 7-9 by a transverse bar or beam 15b with vertical apertures at each end to receive the stanchions, so that a considerable area of a die is engaged, distributing rather than localizing load moving pressure; and also so that narrow loads may be evenly engaged. Where arms 15a are used, dropped down in front of the stanchions, the effective useful range of the latter is extended beyond the confines of the platform for pushing manipulation say of a die in a press.

FIGS. 4-6 inclusive show a typical sequence for loading a die block D from the press bed B onto the lift plat form. The truck approaches the press bed B end-on, so that the rollers 25, 27 are located in proximity to the bed. Cable C with opposite ends secured to the stanchions 15, is strung around the die block and, if necessary, the die is drawn into the position indicated by solid outline D1 in FIG. 4. The auxiliary lift mechanism is actuated to raise the rollers, thereby tilting the end of the die adjacent the truck upwardly to the position of dashed outline D2.

The truck is then backed away from the press, dragging the die on its back edge along the bed and supported at its front end by the rollers, until the position is reached such as the solid outline D3 in FIG. 5. The stanchions are then retracted with the truck stationary, drawing the die further out of the press bed as indicated by the dashed outline D4 in FIG. 5; the lift rollers being gradually dropped in position to bring the front end of the die block into contact with the truck platform 14 before the center of gravity has passed the rollers. When the back edge of the die has approached the front edge of the bed 13 as indicated by D5 in FIG. 6 and the center of gravity of the block has moved beyond the rollers toward the truck platform, the rollers are then raised again to the level of the platform surface, raising the die to the horizontal position D6 whereupon the die may be drawn still further onto the platform; or if size requires it may be transported with the rollers in the last position for support even though the center of gravity lies close to or even slightly beyond the front edge of horizontal surface 14.

The unloading sequence of the manipulations appears in FIGS. 7-9 inclusive. The truck approaches the press bed B endwise to bring the auxiliary lift elevator mechanism into proximity with the frontedge of the bed, the guard structure 35, if desired, serving as an aligning gauge or guide for a straight headon approach; the die, usually transversely disposed on the truck platform, being at the position of the solid outline D1. The stanchions, joined by a transverse bar 15b, are advanced into engagement with the back of the die to push the die forwardly toward the position of the dashed outline D2.

As the die is pushed forward, and before the center of gravity of the die reaches the forward edge of the horizontal surface 14, the rollers are swung up into a position coplanar with the surface 14 (i.e., with top regions tangent to 14 extended) to support the block when and after the center of gravity has reached such forward edge. The lift mechanism is lowered to bring the overhanging forward end of the die from position D2 downward to inclined position D3 with the front edge of the block resting on the press bed, the center of gravity having not yet passed beyond the rollers. Thereafter advancing movement of the stanchions rushes the die block further into the press bed until the stanchions have reached their extreme forward limited motion as indicated by the solid outline D4 in FIG. 8, the center of gravity of the block then lying beyond the rollers.

The auxiliary lift mechanism rollers are again raised to a point above the platform surface, tilting the block further upwardly to dashed position D5 to provide clearance at the back end of the block relative to the truck. The truck is then backed away from the bed, engaging the die with rotatable roller support rather than sliding friction, and the auxiliary lift mechanism is simultaneously lowered until the die block is flat on the press bed and fully supported thereby, since the center of gravity lies over the bed, as indicated by the solid outline 6. The truck is further backed away so that the front of the auxiliary lift mechanism entirely clears the die block, the platform is raised to bring the guard structure 35 to a level for encountering the vertical face of the block; and, as indicated by the dashed outline of the platform in FIG. 9, the truck is then advanced toward the bed to push the block into final position indicated by the dashed outline D7. Where the die has not been placed deep enough into the bed by such manipulation sequence, the arms 15a may be brought to the disposition shown by the dashed outline 15a in FIG. 1 to extend the effective reach of the mechanism. It is to be noted that although the truck here disclosed is of great advantage where the external situs for a load is at a lower level than that attainable by the platform, particular circumstances are conceivable wherein there may be a difference in level between the two surfaces for other reasons, and the overall mechanism may then of course be advantageously used. It is even possible where the platform must be situated at a level lower than the external location to use the auxiliary lift to aid in the load shift, particularly where the lifting device is designed to swing the rollers to a point appreciably above the platform surface.

I claim:

1. An industrial truck adapted for shifting massive loads between a generally horizontal load supporting surface of the truck and an external location at a level below that of said surface, comprising: a vehicle including at one end a vertically shiftable front end loading platform, said platform having a generally horizontal load supporting top surface and a front skirt at the outer end of the platform spaced below said surface, said platform also including an inclined formation sloping from said surface toward said skirt; power-moved stanchion means movable lengthwise of the platform for providing a load shifting force directed lengthwise of the platform; a vertically swingable arm assembly projecting forwardly over the central region of said skirt through an opening in said platform, said assembly having an inner end mounted beneath the platform surface by transverse pivot means and carrying on its outer end transversely disposed horizontal roller means; a hydraulic cylinder unit with a fixed element mounted on said platform beneath said surface and a movable element pivotally connected to said arm assembly for swinging said assemblyfrom a lowermost position with said roller means below said inclined formation to a position at least as high as said surface; and a source of hydraulic fluid pressure and control means therefor directing fluid to and from said unit for swinging said arm assembly, and maintaining the roller means at a selected position.

2. An industrial truck adapted for shifting massive loads between a generally horizontal load supporting surface of the truck and an external location at a level below that of said surface, comprising: a vehicle including at one end a vertically shiftable front end loading platform, said platform having a generally horizontal load supporting top surface; power-moved means for providing a load shifting force directed lengthwise of the platform; a vertically swingable arm assembly projecting forwardly beyond the front edge of said load supporting surface through an opening in said platform below said surface, said assembly having an inner end mounted beneath the platform surface by transverse pivot means and carrying on its outer end, transversely disposed horizontal roller means; a hydraulic cylinder unit with a fixed element mounted on said platform beneath said surface and a movable element pivotally connected to said arm assembly for swinging said assembly from a lowermost position with said roller means spaced entirely below the level of said surface to a position above the level of said surface; and a source of hydraulic fluid pressure and control means therefor adapted for directing fluid to and from said unit for swinging said arm assembly between any selected positions in a range dey fined by the first-named positions and for maintaining the roller means at a selected position in said range,

References Cited in the file of this patent UNITED STATES PATENTS 2,567,335 Herbert Sept. 11, 1951 2,570,726 Smith Oct. 9, 1951 2,586,485 Schroeder Feb. 19, 1952 2,756,885 Ackerman July 31, 1956 2,818,189 Schreck Dec. 31, 1957 

